21. If the gate is given sufficiently large charge, electrons will be attracted to ____________
a) drain region
b) channel region
c) switch region
d) bulk region
Answer: b
If the gate is given a sufficiently large charge, the negative charge carriers, electrons will be attracted from the bulk of the substrate material into the channel region below the oxide.
22. Enhancement mode device acts as ____ switch, depletion-mode acts as _____ switch.
a) open, closed
b) closed, open
c) open, open
d) close, close
Answer: a
Enhancement mode transistor acts as an open switch whereas depletion-mode transistor acts as a normally closed switch.
23. Depletion mode MOSFETs are more commonly used as ____________
a) switches
b) resistors
c) buffers
d) capacitors
Answer: b
Depletion mode MOSFETs are more commonly used as resistors than as switches. As permanently on switch it has high resistance.
24. Enhancement mode MOSFETs are more commonly used as ____________
a) switches
b) resistors
c) buffers
d) capacitors
Answer: a
Enhancement mode MOSFETs are more commonly used as switches and depletion mode devices are more used as resistors.
25. Depletion mode transistor should be large.
a) true
b) false
Answer: a
Depletion mode transistors should be made large that is long and thin to create the large ‘on’ resistance.
26. Which expression is true?
a) charging time < discharging time
b) charging time > discharging time
c) charging time = discharging time
d) charging time and discharging time are not related
Answer: b
When driving a capacitive output load, charging time will be long compared to the discharging time.
27. Overheating in the device occurs due to less number of resistors per unit area.
a) true
b) false
Answer: b
When the number of resistors per unit area increases, the device may not dissipate heat very well. This results in device overheating which leads to its failure.
28. In n channel MOSFET ______________ is constant.
a) channel length
b) channel width
c) channel depth
d) channel concentration
Answer: a
In all n-channel MOSFET transistors, the channel length is constant whereas channel width can be varied.
29. nMOS fabrication process is carried out in ____________
A. thin wafer of a single crystal
B. thin wafer of multiple crystals
C. thick wafer of a single crystal
D. thick wafer of multiple crystals
Answer: A
The nMOS fabrication process is carried out in a thin wafer of a single crystal with high purity.
30. ______________ impurities are added to the wafer of the crystal.
A. n impurities
B. p impurities
C. silicon
D. crystal
Answer: B
p impurities are introduced as the crystal is grown. This increases the hole concentration in the device.
